Gun sighting device



E. J. MARTIN GUN SIGHTING DEVICE Aug. 6, 194s.

Filed 1144.16, 1945 2 sheets-sheet 1 Aug. e, 1946. I E. J; MARTIN '2,405,441v

GUN SIGHTING 'DEVICE v Filed DeC. 16, 1945 2 Sheets-Sheet 2 Snventor www r attorney? Patented Aug. 6, 1946 UNITED STATES PATENT OFFICE* I 2,405,441 i `'GUN sIGHTING Dnvror. Edward J. ll-Iartin, Pleasant Ridge, Mich., assignor to General Motors Corporation, Detroit. Mich., a corporation of Delaware 'Y v f e Application December 16, 194s, serial No. 514,440

. 'gun 'to ,initially set `the sights, thejformer experience has been that it took approximately thir- `teenl to fifteen rounds of ammunition to bring the sights to their requireddegree ,of accuracy. This method also requires theuse of a hundred yard :be seen Ythat by the vuse of this number of rounds of ammunition Aper gun, the expenditure of ammunition in this process WWhere any number of fguns are built is considerably high. There is of Y course the further problem of safety concerned in handling these guns.

It l'is therefore an object :of my invention to'pro- 'vide means for initially adjusting the sights of -a Ari'fievvithout the use of lrifle ammunition.

Itis a further .object of my invention to `provide means for accurately adjusting the sights on a rifie utilizing light rays.

It is a still further object-ofmy invention to provide means' forinitially adjusting the sights lof la rifle Which Will occupy only a 'very limited 'space' and which will permit quick Aadjustment to the proper degree.

` With these and other objects in view which will# 4 Claims. (Cl. 8&-7-4) 6 and a front sight 8. .This rear sight may either be a V groove or a' peep sight, depending upon the rifle supplied bythe manufacturer, Iorder to rproperly align these two sights so that the line through them Will be parallel to the lille through the bore of .the barrel, `I have provided means rifle range and considerable time. It can readily 'become apparent as the Aspecification proceeds,

the embodiments of my invention will be best understood by reference to the following specification and `claims 'and the illustrations in the accompanying-drawings, in which:

f Figure '1 is aside View partially in seotions'how- "ing one for-m of sighting means embodying mynvention; K- v Figure 2v1is a Sectional VveW `taken ron line 2--2 Figure 3 fis a schematic perspective viewshow.-l

in'g'fa modi'edsystem .of adjusting the sights of the rifle according to my invention.

'Referring Anovv more specifically to Figure 1, Vthere is :shown therein ,afgun or zrifle 2 Which is :supported inany ysuitable :support 4 :having .fopenings `:for the stock'and .barrelfof the rifle so vthat it :may :be inserted '.thereinfan-d rremoved easily. The :rifle therefore in Ithis support assumes the position .shown and .is provided with a" .rea'r `'sight which caribe easily and quickly applied to the rifle. vThe first portion which isapplied to the rifle is a unitary member having a cylindrical portion lil which has projecting from its one face ran integral ,rod I2 which extends back into the muzzle of the rifle for an appreciable distance. It might be mentioned at this point that through various investigation it has been discovered that the last four ,inches in the barrel of the rifle determine thev pathicr trajectory of the .bullet and therefore the integral rod I2.is approximate'lyfour dominating portion of the barrel.

The ycylindrical member I0 has a hollow ininches long' and `its position is determined Aby the terior into which projects acentral rod I4 also integral .therewith and which vis in alignment with the oppositely lextending rod I2. This forwardly projecting rod I4 maybe radiallyadjusted within the cavity 4I6 of lthe cylinder l0 by adjusting screws I8 'which are threaded into the cylinder lll from three sides at Aapproximately 120 apart, and-'so' may move the uouter end of this rod I4 within the cavity I6 for yalignment purposes. To

the forward end of this rod I4 is fastened amirrored plate' 2i) vbyanysuitable means suchas spot Welding. a

` 'The secondporton ofthe ,apparatus applied to the'rifle is adapted to serI in oron the sights 6 or 8 and this consists of an elongated cylinder 22 of a telescope having an eye piece `2li movable in one end thereof which inthe example shown 'will be that end nearest the butt or stock and 'which has a suitable lens system therein, such as flens 26, to view the mirrored surface ofthe disc 20. inserted Within eye piece T24 is a small refiectordisc 28 which may eitherbe half vsilvered f cross hairs v3l fsimilar vto those used Yin a great as fat 29V or merely a glass diagonal ,-set in .at approximately a 45m-angle -adjacent an opening'Sil and are 1reflected and the reflected rays can kbe viewedby the eye.

Mounted just ahead of thisangled member 28 and ,in the eyepiece ,2t y area pair of right angled number of opticalinstrumentsl ,et th thefrnt ,and rear portions of the telescope adjustable brackets are provided so that both ends may be moved relatively to the sights. In adjusting sights for rifles it might be necessary to move both the front and the rear sights both horizontally and vertically with respect to the barrel. However, it is seldom necessary to move each sight in both directions Vand in the present instance, while the apparatus could be made to function as above mentioned, it has been found satisfactory to pro- Y vide only vertical adjustment or height with re gard to the front sight and horizontal or trans-.-

y 4and the telescope assembly placed upon the sights verse adjustment with regard to the rear sight and therefore in both instances thek equipment actually used comprises only such adjustment as f j above mentioned, though the drawings of Figure 1 show adjustments in two planes at right angles to each other.

With regard to the front sight, there is provided,Y

a suitable frame such as 34 which carries micrometer adjustment screws 33 and 38 for both horizontal andvertical adjustment; VThe frontend ofY the telescope is therefore supported by this frame between the movable screwends ofthe micrometer mechanisms and' two springbiasing ribbons 4l)y and 42. YA block 44 rigidly secured to the lower surface of the frame 34h`as an opening therein YadaptedV to t over the upwardly projecting end of the front sight 8.. 'Ihus by moving eitherof the micrometer screws, the telescope may be moved horizontally or vertically in either directionwithinithe frame 34 to align the telescope with 4the rifle.- l Y Y vThe same type of frame supports the-rearend of the telescope as shown at 34' andthis also supports v-two micrometer screwadjustm'en'ts 36' and 38', the supporting-block 44 in this instance however having a rearwardly lextending pin 46 which is adapted to lie in the V slot orpeep of the rear sight 6. Theteles'cope is provided with,4

al bracket 48 which is connected to theapproximate center thereofY and which is so formed as to extend around the rifle and support below the same a Yweight 50-which is adapted to maintain thetelescope assembly in the proper position on the sights by gravity. The same may therefore be lifted and placed on the sights, and whenV the rie has been properly adjusted, may be removed without anyv complicated clamping or supporting arrangement,`

The rst step-in the use of vmy equipment is to adjust the bore plug mirror so thatfits'reecting surface is perpendicular'to the axis of the bore plug-itself. This may be `done by mounting the lbore plug in a lathe or fitting itto a muzzle v of a rie.- It is then turned slightly'and adjusted by means of the -adjustingscrews I8 until a spot of lightreflected by the mirror remains stationary.V Of course, once this boreV plug'has been adjusted, it is not necessary to thereafter further adjust the same, but only check itv occa- Vtherifle, and since the supporting blocks`44 and ..44,"which either themselves or through their as-V sociated parts, contact thesights, Vdetermine the as shown in Figure l. 'If in viewing through the telescope the cross hairs do not coincide with the image thereof, theoperator then knows that the sights are not correct. He then turns, for example, the vertical micrometer screwf36 to raise the forward end of the telescope, or lower as the case may be, until the horizontal cross hair positions correspond. When that has been accomplished,

Y the operator then turns the horizontal adjusting micrometer screw 38 in the rear assembly until the vertical cross hairs and their image coincide. The reading on each of these two micrometer screwsAfrom the scales such as 52 which are found thereon, gives an index as to the amount that the sights must be -moved or ground to be correct.

In this respect, the front sight is always provided too high so that it may be ground olf to the proper height andthe rear sight is in a horizontal slot sothat-it can be moved back and forth as the need demands. The telescope is then ofcourse removed-and the parts adjusted as indicated and the telescope then replaced to see'if the adjustmentis now correct. This is repeated until the micrometer screws' can be placed in their normal zero position and the cross hairs coincide with their image as reflected. y j lIn this system it is of. course necessary-for an operator t0 continuously'view through the eye piece'the mirroredsurface and'make small adjustments which may be fatiguing. I have therefore provided' a modified optical arrangement for adjusting sights in which the image of cross hairs or vits equivalent may be thrown upon a screen so thatit will not be necessary for an operator to continuously squint through a telescope. In this instance, as before, the rie is supported in a suitable block (not shown in Fig. 3) and in this case the muzzle plug is supported in the end of the muzzle as before, which' is shown diagrammatically'in Fig. 3 at 6B.' However, in this instance the forward face of the mirror 20 is polished to form a reflecting surface 'rather than the surface facing the rifle.A

FThe Itelescope'assembly is replaced in this instance by an ordinary straight bar 62 having a supporting block 64 mounted on the front sight and a second supportingV block 66-having a pin T58 which projects into the opening in the rear Y instance happens to be broken away, h'as a pendulum rod on the broken away portion (not shown) similar to 48 and50 of Figure 1 to maintain it in Y position on top of the sights. Applied to the forf ward surface of the bar 62 and at right angles to the axis thereof is a second mirror 10 whose surface is adapted to lie substantially parallel to the mirror 60, depending upon the Valignment of .the ybar 62 with th'e bore of the rifle barrel.

after which they proceed to a mirror 82 which is merely a reversed mirror to bring them back to a screen et. This screen may be viewed either directly or through an enlarging lens, such as 86, for micrometer adjustment. A series of colored filters such as 88 and 9D shown in dotted lines v adjacent to theV lens 80 may be applied if desired. These lters may if more easily applied be located adjacent the mirrors 6E) and li) if desired.

With this equipment, assuming of course that the muzzle plug 60 has been adjusted so that the mirror is perpendicular to the barrel or rod I2 which projects back into the barrel as before described, this plug is then inserted into the end of the gun barrel, and by using a master rifle to initially set the equipment, the bar 62 is laid upon the front andV rear sights 8 and t'. The light l2 is then energized. and a cross beam of rays is projected upon the mirrors 6G and lil. If the two mirrors are exactly parallel, a single image of the crossed beams projecting through slots M will fall upon the mirror 82 and therefore upon the screen 84. This Will indicate that the axis of the bar 52 is parallel with the bore of e bar 62 so that it will lie parallel to the axis of the rifle barrel. Thus through micrometric adjustment means similar to that shown in Figure 1 and illustrated diagrammatically only as supporting blocks 64, 65 and 68, these axes may be aligned. As before mentioned, for all practical purposes if the adjustment on the front sight is vertical and that on th'e rear horizontal, most sighting means can be properly aligned. I have indicated such adjustment by arrows in Figure 3.

The master riiie is then removed and these two parts are placed in a rifle to be tested. If there appears two images of the slots in the disc 'i6 not in coincidence on the screen 84, the micrometers at the front and rear plugs are moved until the same are coincident. This adjustment as read on the micrometer screws th'en gives an indication as to how far these parts must be moved or ground away to bring them into alignment and such correction is then made following which a second check is made by the equipment shown in Figure 3. This is repeated until a single image of the cross slots appears.

In order to facilitate the alignment, if a color lter 88 is inserted either as shown in dotted lines or adjacent the mirror 60, and a second color filter of complementary'color such as 90 is applied to intercept the rays from the second mirror, it will be easier for the operator to superimpose these two images. By using such complementary colors, such, for example, as red and green, two diiferent images of the slots will appear on the screen, one red and one green, if the equipment is not in alignment. However, upon bringing these two images into coincidence, a yellow cross will appear which will be a very accurate indication to the operator that the two crosses are coincident and therefore assist in the adjustment.

It will be obvious that with this equipment only a relatively small area or test location is required;

iii)

that it is highly accurate and not subject to errors usually` occasioned by short sighting means, but that it accurately provides indications as to when a line through the sights and that through the axis of the barrel are parallel and that the system as a whole is simple, rugged and easily operated.

I claim:

l. In aligning means for guns having visible sights thereon, light reflecting means mounted on the barrel of the gun whose position is determined by the bore thereof, a second light reflecting means mounted upon the sights and whose position is determined by the alignment thereof,

means for projecting a beam having dei-mite configuration onto the two reflecting surfaces simu.- taneously, and means operatively positioned with respect to the light reflecting means to project said rays onto an image plane in such a way that the coincidence of Ithese rays may be observed.

2. In aligning means for guns having visible sights thereon, light reflecting means mounted on the barrel of the gun whose position is determined by the bore thereof, a second light reecting means mounted upon the sights and whose position is determined by the alignment thereof, means for projecting a beam having a definite configuration onto the two reflecting surfaces simultaneously, means operatively positioned with respect to the light reflecting means to project said rays onto an image plane in such a Way that the coincidence of these rays may be observed, ancl means to adjust the position of the second light refiecting means with respect to the sights to bring the rays into coincidence.

3. In aligning means for guns having visible sights thereon, light reflecting means mounted on the barrel of the gun whose position is determined by the bore thereof, a second light reecting means ymounted upon the sights and whose position is determined by the alignment thereof, means for projecting a beam having definite configuration onto the two reecting surfaces simultaneously, means operatively positioned With respect to the light reflecting means to project said rays onto an image plane in such a Way that the coincidence of these rays may be observed, and color filter means interposed in the paths of the two rays to give each a different identifying color.

4. In aligning means for guns having sighting means thereon, a pair of reflecting surfaces, means extending into the bore of the gun for mounting one of the surfaces, means engaging the sights for supporting the second surface adjustably with repect to said sights, light means for projecting a predetermined pattern on both surfaces, means for receiving the reected rays, said reflecting surfaces being so positioned and associated with respect to one another and to the receiving m'eans that the reiiected rays are directed to said receiving means, means to adjust the means supporting the second surface to bring the two images on said receiving means into coincidence, and indicating means on the adjustable means to provide information as to corrective movement of the sights.

EDWARD J. MARTIN. 

